Summary of Compound Detections and Concentrations

The following tables summarize data collected for NAWQA studies during 1992-1995 by showing results for the Ozark Plateaus Study Unit compared to the NAWQA national range for each compound detected. The data were collected at a wide variety of places and times. In order to represent the wide concentration ranges observed among Study Units, logarithmic scales are used to emphasize the general magnitude of concentrations (such as 10, 100, or 1,000), rather than the precise number. The complete dataset used to construct these tables is available upon request. These tables were designed and compiled by Sarah Ryker, Jonathon Scott, and Alan Haggland, U. S. Geological Survey.

Freshwater-chronic criterion for the protection of aquatic life aDrinking water standard or guideline aRange of surface-water detections in all 20 NAWQA Study Units
Range of ground-water detections in all 20 NAWQA Study Units
Detection in the Ozark Plateaus Study Unit

Guideline for the protection of aquatic lifeeRange of detections in fish and clam tissue in all 20 Study Units
Range of detections in bed sediment in all 20 NAWQA Study Units
Detection in bed sediment or fish tissue in the Ozark Plateaus Study Unit
Detection in clam tissue in the Ozark Plateaus Study Unit

Trace elements

No non-detects

a Selected water-quality standards and guidelines
(Gilliom and others, in press).

b Rates of detection are based on the number of analyses and detections in the Study Unit, not on national data. Rates of detection for herbicides and insecticides were computed by only counting detections equal to or greater than 0.01 µg/L in order to facilitate equal comparisons among compounds, which had widely varying detection limits. For herbicides and insecticides, a detection rate of "<1%" means that all detections are less than 0.01 µg/L, or the detection rate rounds to less than 1 percent. For other compound groups, all detections were counted and minimum detection limits for most compounds were similar to the lower end of the national ranges shown. Method detection limits for all compounds in these tables are summarized in
(Gilliom and others, in press).

c Detections of these compounds are reliable, but concentrations are determined with greater uncertainty than for the other compounds and are reported as estimated values
(Zaugg and others, 1995).

d The guideline for methyl tert-butyl ether is between 20 and 40 µg/L; if the tentative cancer classification C is accepted, the lifetime health advisory will be 20 µg/L
(Gilliom and others, in press).